Half of all phone calls by 2009 will be made on mobile phones, with mobile operators launching an 'aggressive assault' on fixed voice services, analysts predict.

According to research by Analysys, the most attractive prospect for mobile operators - but also the most challenging - is to encourage users to give up their fixed voice services altogether.

Fixed lines will still be needed to support internet access and will thus limit the decline in fixed voice channels between 2004 to 2006 to one per cent, said the research firm.

But it warned that this would not prevent what is likely to be a bitter battle for voice minutes between fixed and mobile operators.

The Analysys report, Road to Fixed-Mobile Substitution Starts with 3G, found that mobile operators will need to address fundamental issues such as tariffs, interconnect pricing, network quality, consumer apathy and internet access, in order to persuade consumers to ditch their fixed lines.

3G will be a key enabler in this battle. Report co-author Mark Heath said: "The introduction of 3G potentially provides a network cost-per-minute one-fifth that of GSM."

"However, 3G roll-out must deliver the necessary wide-area and in-building coverage to support a fixed-substitution strategy."

The analyst warned that many consumers will not consider giving up their fixed line unless there is an alternative means of internet access, whether in the form of DSL unbundled from fixed voice or broadband wireless access using one of the emerging high-speed wireless technologies.

Alternative means of connecting to the internet, however, could accelerate the decline in fixed voice channels to almost 10 per cent a year from 2006 to 2009, further accelerating the migration of voice traffic from fixed to mobile.

The report predicted that over the next five years the total volume of voice calls in western Europe will increase by 10 per cent while the volume of calls by mobile phones will increase by 94 per cent, with the result that 50 per cent of voice call minutes will be generated by mobile phones in 2009.